The synthesis and lactamase inhibitory activity of 6-(carboxymethylene)penicillins and 7-(carboxymethylene)cephalosporins

A series of 6-(carboxymethylene)penicillinates and 7-(carboxymethylene)cephalosporanates were synthesized and evaluated as inhibitors of one type A and two type C β-lactamases. Disodium 6-(carboxymethylene)penicillinate sulfone (15) showed broad spectrum activity. A kinetic analysis demonstrated that 15 was a potent, partially irreversible inhibitor of the β-lactamase derived from Enterobacter cloacae P99.